— What water filtration methods are available in the world?
— Three groups can be distinguished.
The first is mechanical filtration through networks and porous structures such as sponges. Using such methods, you can remove from water all kinds of particles that are insoluble in it: sand, rust, lime (formed by oxidation of the metal surface. – “socialbites.ca”), clay.
The second is sorption. A substance is poured into the filter, which, through chemical interaction, “binds” harmful particles and does not allow them to pass further. For example, activated carbon.
The third is reverse osmosis technology. Imagine a screw juicer. You put fruit in it and the juice flows from one side and the pulp flows from the other. This filter is also designed. In it, water is divided into two streams: clean and dirty.
— Is clean water mechanically separated from dirty water?
– No, this is an electrostatic method. The filter has a membrane that only allows water molecules to pass through and traps any impurities. Water molecules have no charge. The main pollutants in our water are positively charged cations and negatively charged anions. You apply pressurized water to the membrane. The membrane repels charged particles but allows water to pass.
— What other water filtration methods are available?
— There is biological and chemical treatment.
During biological purification, bacteria that eat harmful substances are added to the water and the water remains clean. Over time, they die and activated sludge is formed. This method is used in wastewater treatment plants.
Chemical refining is the addition of a chemical such as a coagulant or flocculant. They bind and precipitate contaminants, then we filter or settle the water.
— There are also ultraviolet lamps for water purification. How do they work?
— They disinfect but do not clean. The composition of water does not change when illuminated with a UV lamp.
— How is drinking water prepared in the city?
— The method of purification of city tap water depends on the source of the liquid.
Mechanical filtration is a mandatory stage of purification, it all starts with it. If the city’s water is very clean, this is where it ends.
But often this method is supplemented by chemical cleaning using coagulants and flocculants. Sometimes ozonation, addition of powdered activated carbon or membrane cleaning is used.
— At what stage is chlorine added to water?
– It is always used last.
— So what is the final composition of this water?
— We removed some large particles and organic matter from this water. However, the salt composition did not change. There was only so much salt left.
— Is this how water comes to the tap?
— When water reaches the tap, it “captures” pollution, called secondary pollution. Usually these are iron impurities or manganese if found in water pipes.
Water can also “trap” some microbiology because bacteria can grow in old pipes.
But they will die along the way because chlorine is added to the water.
— How much chlorine is usually added to water?
— When you turn on the tap at home, there is between 0.3 and 0.5 mg of active chlorine per liter of water. In the water treatment plant, chlorine is added to the water after it passes through all the pipes, leaving chlorine at the outlet. It is known to evaporate from water over time.
— Is active chlorine harmful?
– Definitely. First of all, it smells bad. The latter is active and can undergo chemical reactions. If your outlet water is clean and does not have any microorganisms or organic residues, it will evaporate over time.
But if there are other substances in your water – for example, you poured water from the tap and began to prepare broth with it, active chlorine will begin to enter into chemical reactions with substances in the water. Then no one knows what the outcome will be.
– Can’t chlorine be removed by boiling?
“The question is what will happen first: will it evaporate or will it interact?”
— Is rust also harmful to the body?
– It’s just a particle that doesn’t dissolve in water. This is more unpleasant than harmful. You ate the pebble, it passed through it and came out, nothing happened to you.
– What about salt?
—From the point of view of salts the problem is the most difficult. Because it is necessary to keep the good and eliminate the bad.
There are useful salts – sodium and potassium. Our body needs them, they are needed for blood, which is itself salt water. For this reason, distilled water is not very useful. This water always needs to be further enriched. There are borderline salts of calcium and magnesium. The body also needs them for the functioning of the heart and muscles, but in small doses.
The hardness of the water depends on its quantity: If you see a large amount of limescale in the kettle, the same formations will occur inside your body. These are kidney or gallstones.
There are also harmful salts of iron, manganese, lead, copper, nickel and heavy metals. They definitely need to be removed.
— We are discussing tap water. What about well water and water from wells?
— The city water administration analyzes water daily according to a large number of indicators (about 40-50 of them), so we always know the approximate composition of water. Mechanical and organic contaminants, salts and dissolved gases will be present in the well.
I have been working with water for 20 years, and during this time it seems to me that I have seen everything: wells containing arsenic, boron, non-ferrous metals, radioactivity. At the first stage after drilling the well, it is important to test the water for the maximum number of indicators.
– Well, if you boil the water, can’t you filter it?
– Let’s find out what happens when water boils. First, boiling water releases chlorine. But if there are any organic contaminants there, they have remained there and can interact with that chlorine before all of it is removed.
Secondly, lime has fallen, that is, the salt composition has partially adjusted and the hardness of the water has decreased. But nothing will happen to heavy metals and dissolved iron. Therefore, it is better to filter the water.
— What filters are currently available on the Russian market?
— There are three major groups: pitcher filters, three-bottle under-sink filters, and reverse osmosis filters.
If we talk about the differences, the jug is cheaper, you can take it to the dacha, but the cassette needs to be changed frequently and wait until the water is filtered. Three-stage ones are more expensive, they are connected to the system, but the cartridges are less replaceable – they can work from six months to a year, plus you do not have to wait for the water to be filtered.
Others are significantly more expensive, take up more space under the sink, and have a complicated installation process because they require connection to the drain. However, they can purify almost any water. Here you can sleep peacefully, if above your city there is a chemical plant that opens the valves at night and throws into the water something that the water utility cannot even dream of – it will not get into your tap. Osmosis will clean everything, guaranteed.
— Does this also apply to wells?
— This filter cannot be installed in the entire private house. Reverse osmosis quadruples water consumption. The water is divided into two branches, only 20% of the water is cleaned and ends up in the tap, the remaining 80% becomes water with pollutants and goes to the drain.
It is also an antibiotic in the field of reverse osmosis water filters. This is a powerful solution that can help in the most serious cases. It can purify water that traditional filters cannot. However, using it has some side effects.
Osmosis gives you pure H2O. But the body needs a certain salt content, so you will need to further enrich the water. In no case should you combine such use of pure water with a low-salt diet. That’s why I recommend using osmosis only in cases where the problem cannot be solved by other means.
— If there is a well on the land and you do not know what is in the water, does it make sense to install a reverse osmosis system?
— First of all, you need to do a detailed water analysis. There are situations when you drill a well and you cannot do anything with it, just look for another source of water. Radioactivity is one of these situations. When semi-sea water flows through your well, there is also a very high hardness. Clay is also difficult to deal with. It is so thin that it penetrates everywhere and clogs any cleaning system very quickly. Especially if the water contains white clay – kaolin.
— Then how to organize filtering at the dacha?
— You have a well, you have water analyzed and the filtering system is selected based on the results. The main difference between a house and an apartment is that the volume of water is much larger. For this reason, the system is designed so that the filter cannot be changed. They provide a regeneration system: washing the filter and restoring filtering ability.
Slightly different principles and hardware design are used, resulting in an automatic control unit. He knows how much water is being filtered, and he knows that the regeneration process doesn’t need to start while the whole family is sitting down for dinner, so he does it at night.
— Is it possible to somehow improve the water and make it healthier?
– Yes. Instead of drinking nutritional supplements and vitamins, we can mineralize water using filters.
The truth is, when you take vitamins, you absorb about 10 to 50% of the nutrients. In addition, when the pill is taken, the amount of the substance in the body jumps rapidly and then decreases. None of these are very good.
You can make the filter dose the amount of beneficial substances and you will constantly receive them with water.
– How to do it?
— There are filters on the Russian market that can dose magnesium, zinc and silicates. Of course, you cannot add the entire vitamin composition to water, but some microelements yes.
— What can you say about the water called hydrogen water?
— I will not believe in the benefits of hydrogen water until the scientific results are shown to me.
— Alkaline water activators are also sold. Are they needed?
— Alkaline water has an above-average pH and a certain redox potential. It is possible to increase the pH of the water, but we have doubts about its restoration potential. We made many experiments with alkaline water but could not prove its beneficial properties.
— What can you say about the water ionizers sold?
— There are ionizers, there are so-called structurators, but all of them are not scientifically proven. For example, you can check and display the features of a filter, measure how much water it filters, how well it filters, and how long it takes to filter it. In the case of ionizers and structurators, properties cannot be controlled. Therefore, it is better to purchase devices with proven effectiveness.